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The Goodman B1378701 5-Pin Wiring Harness is a genuine OEM connector assembly built for the Goodman GMP050-3 gas furnace. This 5-pin harness links a dedicated sub-circuit — such as the igniter, gas valve, or limit string — to the furnace control system. A degraded or loose harness is a common hidden cause of ignition faults and intermittent shutdowns, and replacing it with the factory part eliminates flaky connections at the source.
The genuine Goodman harness matches the exact connector keying, pin spacing, and wire colors of the original, so it drops straight in with no guesswork. Aftermarket alternatives frequently demand hand-splicing that can loosen over time and create resistance-driven heat. For dependable, code-compliant service, OEM wins.
Easy to Moderate. With power and gas off, unplug the failed harness and snap the replacement into place, matching each connector. A basic tool kit and a service diagram are all that's typically required — a great option for a competent DIYer or professional tech.